Plant for thermolysis and energetic upgrading of waste products

ABSTRACT

The invention concerns a plant for the thermolysis of waste products containing an organic fraction, and for simultaneous energetically upgrading these waste products comprising: a unit for loading and supplying the waste products to be treated; a thermolysis reactor for thermal dissociation under reduced pressure at high temperature. The invention is characterized in that it comprises: upstream and downstream of the reactor, a lock chamber for maintaining a partial vacuum in the reactor for ensuring thermolysis in an atmosphere with low oxygen content; first means for recuperating, in the upper part of the reactor, the organic gas fraction formed during thermolysis, and for bringing this fraction to a combustion chamber supplying a steam generator; second means for recuperating at the bottom of the reactor the solid carbon products formed during thermolysis, and for bringing these solid products to a combustion chamber supplying a steam generator or an evacuating system. The gas of the combustion chamber and the steam produced by the steam generator, in turn supply the unit producing the waste products and/or means for drying in advance of the waste products provided just upstream of the reactor.

TECHNICAL FIELD

The invention relates to a plant for the treatment by thermolysis andsimultaneously for the upgrading with regard to energy of wastecomprising an organic fraction.

PRIOR ART

The treatment of waste comprising an organic fraction is well known, inparticular in the treatment of waste as diverse as automobile shredderresidues (ASR), hospital waste, also known as healthcare activity waste,old tyres, green waste or waste resulting from biomasses, municipal anddomestic waste, or meat meal, but also treatment plant sludges and thesludges from various petroleum products. The treatment of waste of thesetypes is becoming increasingly worrying as a result of the increasinglylarge amounts to be treated and of the increase in the cost of thesetreatments.

The thermal dissociation of waste comprising an organic fraction underreduced pressure and at high material temperature is well known (see inparticular document U.S. Pat. No. 4,077,868, U.S. Pat. No. 4,833,021 andCA-A-1,163,595).

In essence, a plant for the thermal dissociation at reduced pressure ofwaste comprising an organic fraction essentially comprises:

a unit for loading and for introducing the waste to be treated;

and a reactor for thermal dissociation under reduced pressure and athigh temperature, for example at a temperature of between 400 and 1000°C., in particular in the region of 500° C., under a pressure of between0.1 and 1 atmosphere.

In the document WO-96/11742, the Applicant Company described a plant ofthe type in question in which two chambers, placed in parallel, arepositioned between the introduction means and the reactor, each of thesechambers being connected to the introduction means of the reactor, thusallowing one of the two chambers to be loaded at atmospheric pressurewhile the other is being discharged at reduced pressure into thereactor. This batchwise/continuous plant, well suited to the treatmentof large amounts, exhibits the disadvantage, however, of requiringsignificant investment.

Furthermore, the production of oils by condensation during the treatmentis, on a practical level, difficult to manage industrially.

In addition, and as said above, the destruction of meat meal unfit foranimal consumption is becoming worrying, in particular with the risk ofthe presence of prions in this meal, so that several techniques havebeen provided to date for the incineration of meal.

The first technique consists in mixing this meal with municipal wasteand in then pyrolysing the combined mixture in municipal incinerators,which are known to be already overloaded. Furthermore, the smallparticle size of this meal leads to the risk of it being swept away intothe air, interfering with the operation of the incinerators. Thistechnique is so expensive that it has not experienced any development.

Provision has also been made to incinerate this meal in inclined rotarykilns. Here again, the small particle size of this meal leads to therisk of it being swept away into the air and the flow in the kilns isoften not very good. Finally, the flue gases produced have to be treatedwith special equipment which places a crippling burden on the cost ofthe plant.

The invention overcomes these disadvantages. It is targeted at a plantfor the treatment by thermolysis of waste and for the upgrading withregard to energy of this waste which is well suited to the treatment ofwaste of the most varied kinds, in small and medium volumes, with a goodratio between investment and operation. It is more particularly targetedat a plant of the type in question which is reliable and robust andwhich has operating conditions which scrupulously respect theenvironment.

Another object of the invention is to provide a plant which can carryout a complete treatment of the thermolysis by-products until the finalwaste is obtained, that is to say waste which cannot be upgraded undercurrent economic conditions.

The invention is targeted at a plant of the type in question in whichthe energy produced during the treatment is recovered in order tooperate, in part and autonomously, the plant itself and part of the unitwhich can produce this waste.

SUMMARY OF THE INVENTION

The invention relates to a plant for the treatment by thermolysis ofwaste comprising an organic fraction and simultaneously for theupgrading with regard to energy of this waste of the type essentiallycomprising:

a unit for loading and for introducing the waste to be treated;

a reactor for thermal dissociation thermolysis under reduced pressure athigh temperature,

characterized

in that it comprises:

upstream and downstream of the reactor, an isolation means intended tomaintain a partial vacuum in the reactor in order to ensure thermolysisin an atmosphere with a very low oxygen content;

first means for recovering, in the upper part of the reactor, thegaseous organic fraction formed during the thermolysis and forintroducing this gaseous fraction into a combustion chamber feeding asteam generator;

second means for recovering, at the bottom of the reactor, the solidcarbonaceous products formed during the thermolysis and for introducingthese solid products into a combustion chamber feeding a steam generatoror a discharge system;

and in that the gases from the combustion chamber and the steam producedby the steam generator in their turn feed the unit in which the waste isproduced and/or a means for predrying the waste positioned immediatelyupstream of the reactor.

In other words, the invention consists in heating the waste exhibiting acontrolled particle size under conditions suitable for dissociating thiswaste essentially into two phases, respectively a gas phase and a solidphase, this being carried out in the virtual absence of oxygen but underreduced pressure, indeed even under a gaseous atmosphere.

The invention consists in recovering the gas phase and the solid phasein order to upgrade them by producing energy in a combustion chamberintended to heat steam which in its turn feeds the unit in which wasteis produced and/or is targeted at predrying the waste before it arrivesat the reactor.

In practice, the thermolysis, also denoted under the term of“pyrolysis”, is carried out at a temperature of between 400 and 1000°C., in particular in the region of 500° C., with a pressure in thereactor of 5000 to 40,000, preferably 10,000, pascals below atmosphericpressure. The residence time of the waste in this reactor is of theorder of several tens of minutes, for example of the order of thirtyminutes.

As already said, depending on the nature of the waste to be treated, thelatter is advantageously premilled in order to exhibit a controlled,indeed even homogeneous, particle size and physical consistency.

In practice, a particle size is defined of between 1 and 10 centimetres,these limits being in no way limiting.

Likewise, the waste can advantageously be subjected to a predryingintended to lower the water content in this waste. This heating, carriedout in an appropriate chamber, can, depending on the nature of the wasteto be treated, be carried out in two ways, namely directly orindirectly. In the direct drying, the mass of the waste is heated bycirculation of hot air or of steam recycled from the generatorcharacteristic of the invention or of hot air recycled from thecombustion chamber. This method of predrying is particularly appropriatefor waste with a low volatile solid fraction (dust), such as ASR. Whentreatment plant sludges are treated, it is preferable to carry outindirect heating, that is to say to heat the chamber externally, whileproviding a degree of mixing intended to break up the product in orderto increase the contact surface with the air.

In an advantageous embodiment, a means for adding an agent for theneutralization of the aggressive components, such as, for example,halogens or sulphur, which makes it possible to avoid the subsequentpresence of harmful compounds (SO₂, HCl, HF) in atmospheric discharges,is positioned in the path of the waste between the introduction deviceand the reactor. This neutralization agent, such as, for example,calcium carbonate, is incorporated in the milled waste as it is conveyedbetween the introduction device and the thermolysis reactor. Thismilling of the waste allows better distribution of the neutralizingagent and consequently better effectiveness of this neutralization.

The thermolysis reactor, preceded by the isolation means characteristicof the invention, operates in the absence of oxygen at a temperature, asalready said, of between 400 and 1000° C., preferably in the region of500° C., and the pressure in the reactor is maintained from 5000 to40,000, preferably 10,000, pascals below atmospheric pressure. Itfollows that the waste to be treated, which generally progresses forwardas thin layers, then decomposes under the effect of the heat into twoby-products, respectively a gas, for substantially two-thirds, and asolid carbonaceous residue, for substantially a third. The residence andflow time in the reactor is several tens of minutes, in particularthirty minutes. The reactor is heated by appropriate means, such aselectricity, in particular.

According to the invention, the two by-products from the thermolysis,respectively the gas and the solid carbonaceous residue, are recovered,the first at the top of the reactor and the second at the bottom of thelatter.

According to another characteristic of the invention, the plantcomprises at least one isolation means positioned upstream anddownstream of the reactor. This isolation means can be formed in anyknown way, for example by a helical compression screw, by pumps, byguillotine valves or the like.

According to another characteristic of the invention, the thermolysisgases recovered at the top of the reactor are conveyed under the effectof suction to a combustion chamber which in its turn feeds a steamgenerator. It is important for the gaseous thermolysis fraction to bemaintained at high temperature during the transfer from the reactor tothe combustion chamber. At the same time, the solid carbonaceousproducts recovered at the bottom of the reactor are conveyed to anothercombustion chamber in order to be incinerated therein, this secondchamber also in its turn feeding another steam generator, or, failingthis, a discharge system for the purpose of a final upgrading, indeedeven disposal on a landfill site.

More specifically, when the starting material comprises a pollutant, thetreatment by thermolysis makes it possible to concentrate the pollutantin one of the two by-products, generally the solid by-product, and thusto carry out the treatment of the flue gases on only a portion of theproducts and not on all the products, which is reflected by anappreciable saving.

The solid carbonaceous product obtained after thermolysis canadvantageously be separated into two by-products, a non-combustibleproduct and a combustible product, only the said combustible productbeing conveyed into the combustion chamber, the noncombustible productbeing upgraded.

Thus, in the case of the treatment of automobile shredder residues, thenon-combustible metal is separated from the combustible fraction, whichmakes it possible to improve the output and the efficiency of the plant.

In a simplified embodiment, the thermolysis gases and the solidcarbonaceous residues produced by the reactor are conveyed to the samecombustion chamber which feeds one and the same steam generator. In andalternative form, the combustion chamber comprises two furnaces,respectively a first furnace for the solid carbonaceous products and asecond for the gases.

This separate combustion of the two by-products, gaseous and solidrespectively, makes it possible to optimize the quality of thecombustion and consequently the outputs. The hot combustion gases aresubsequently combined in order to be upgraded in the form of energy forthe production of steam or of hot water.

As already said, before combining the hot combustion gases, it ispossible, after having separated the polluting solid by-product, totreat the flue gas resulting from the combustion of this by-product in aunit for the treatment of flue gases, which unit is intended to recoverthe pollutants in order for them to be disposed of on a landfill sitefor final waste.

Thus, it could be determined that the treatment of 200 kilos per hour ofhospital waste makes it possible to produce approximately 600 kilos perhour of steam at 8 bar.

After having been upgraded, the combustion gases are discharged to theatmosphere via a conventional chimney under conditions which prevent theformation of a plume.

On the other hand, the solid carbonaceous products, after having beenupgraded in the combustion chamber, result in markedly lower amounts offinal waste, such as ash, than those of the clinker resulting fromconventional incineration, in particular when, before combustion, thenon-combustible metallic fraction and the combustible fraction areseparated.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 diagrammatically illustrates a plant in accordance with theinvention.

FIGS. 2 and 3 show this same plant in outline perspective view,respectively three-quarter top view (FIG. 2) and three-quarter side view(FIG. 3).

FIG. 4 is an outline diagrammatic representation of a first simplifiedplant in accordance with the invention.

FIG. 5 is a diagrammatic representation of a second plant of theinvention.

FIG. 6 is a representation of the plant of the invention applied to thetreatment of meat meal.

MANNER OF IMPLEMENTING THE INVENTION

With reference to FIGS. 1 to 3, the plant in accordance with theinvention comprises a receiving station (1) for the waste (2) to betreated comprising an organic fraction, such as hospital waste, oldtyres, automobile shredder residues (ASR), green waste or biomass waste,municipal or domestic waste, treatment plant sludges, or indeed evenpetroleum waste.

This waste (2) is introduced into a milling unit (3) intended to bringit to a controlled particle size, preferably a homogeneous particlesize. The milled waste is subsequently introduced into a hopper (4),then into an isolation means (5), and from there into a directly orindirectly heated drying chamber (6). The vapours (7) resulting from thedrying are captured at the top of the chamber (6) via a pipeline (8) inorder to be introduced into the combustion chamber. The dried waste (10)first of all has a neutralizing agent, such as calcium carbonate, addedto it in (11) and is then subsequently conveyed via a conveyor (12) tothe inlet of the reactor (13).

In an alternative form, the waste (2) is stored in an intermediatestorage silo upstream of the reactor (13) and is directly conveyed tothe latter, without prior milling and drying stages.

This thermolysis reactor (13) can be of the type pf that which isdisclosed in the document WO-96/11742 of the Applicant Company, inparticular in FIGS. 6, 9 and 10 of this document, or of anotherequivalent known type. This reactor (13) is preferably heated withelectricity. It is important for this reactor (13), heated at atemperature in the region of 500° C. with a partial vacuum of the orderof ten thousand (10,000) pascals below atmospheric pressure, to operatewith a deficiency of oxygen. The residence time of the waste (10) inthis reactor is approximately thirty minutes.

To avoid any ignition of the carbon present in the waste on contact withoxygen which might be accidentally introduced into the reactor,provision is made for the installation of a supply of nitrogen at thereactor.

The thermolysis brings about the formation of two by-products,respectively a gaseous organic fraction recovered upwards via thepipeline (15) and a fraction of solid carbonaceous products recovereddownwards (18).

According to one characteristic of the invention, the plant comprisesmeans (15) for recovering at the top of the reactor (13), in particularusing a pipeline and a fan (16), the gaseous organic fraction formedduring the thermolysis in order to introduce it into a combustionchamber (20). This combustion chamber, of horizontal cylindrical type,has an inlet (21) for propane gas which makes it possible to supply anextra charge, to guarantee that the temperature is maintained during thestart-up and shutdown phases and to provide a pilot light. Thiscombustion chamber (20) in its turn feeds the steam generator (22), forexample of the double-circulation boiler type fed with water (23).

In an advantageous embodiment, the clean combustion gases from thecombustion chamber (20) are introduced via a pipe (25) into the dryer(6), in particular to provide direct drying of the waste to be treated.The steam produced by the generator (22) is introduced via a pipe (26)into the same dryer (6), in order to provide indirect drying of thewaste to be treated, or in order to be used at the site on which thewaste (2) is produced.

The reference (30) denotes a fan for introducing combustion air and thereference (31) the burner of the combustion chamber (20). In the sameway, the pipe (8) for extraction of the vapours from the dryer (6) isused in combination with an extraction fan (9) which introduces thesevapours into the same combustion chamber (20).

The flue gases emerging from the generator (22) are introduced via thepipe (35) into a cyclone (36), from where they are extracted by a fan(37) connected to the external chimney (38) for discharge to theatmosphere.

In an advantageous alternative form, the receiving area (1) for thewaste (2) is surmounted by a hood (40) used in combination with a pipe(41) introducing low pressure air into the combustion chamber (20) inorder to act as additional combustion air. In this way, by virtue of afan which is not represented, the vapours naturally given off by waste,in particular hospital waste, are discharged and then incinerated and donot disperse in the treatment chamber.

According to another characteristic of the invention, the solidcarbonaceous residues (18) formed during the thermolysis first of allpass through an isolation means (50) analogous to (5) and then onto aconveyor (51) which makes it possible to extract these residues at thebottom of the reactor (13).

The solid carbonaceous residues (18) are advantageously cooledindirectly before or after the isolation means (50), so as to avoid anyrisk of explosion.

In addition, for large plants, the isolation means (50) can be composedof two parallel silos filled under reduced pressure and alternatelyemptied at atmospheric pressure.

These solid carbonaceous residues (18) are rich in carbon but also inpollutants, such as chlorine or sulphur, and comprise inorganicfractions, such as metal, glass, pebbles, indeed even multiple residues.These residues, which are embedded in the very fine pulverulent powderresulting from the thermolysis of the organic fraction, are screened in(52) according to their particle size and their nature, making itpossible to obtain a carbonaceous fraction (53) and an inorganicfraction (71, 75).

The carbonaceous fraction (53) is introduced into a second combustionchamber (60), analogous to (20), which is also fed with propane gas (61)and the outlet of which for gases (62), analogous to (25), can beconnected to the dryer (6). This combustion chamber is, as above, usedin combination with a steam generator (65) fed with water (66) in orderto provide steam in (67), analogous to (26), in order also to beconnected to the dryer (6). The combustion ash is removed in (68) inorder to be disposed of on a landfill site.

The inorganic fraction (71, 75), essentially comprising metals, glass,pebbles or final waste, forms the subject of an additional screening inorder to store (72) and then recover the recyclable materials (71), onthe one hand, and the non-upgradable fraction (75) composed of solidresidues, on the other hand, which are discharged (76) in order to bedisposed of on a landfill site (77).

According to an advantageous embodiment, the screening carried out in(52) consists in separating the ferrous metals from the carbonaceousfraction (53) obtained after thermolysis, by magnetic separation, and atthe same time separating the non-ferrous metals from the saidcarbonaceous fraction, by induction separation.

The ferrous metals obtained are subsequently upgraded, while thenon-ferrous metals are subjected to another screening, making itpossible to separate the inorganic part, on the one hand, and thus toobtain a carbonaceous powder, on the other hand, which powder issubsequently conveyed to the combustion chamber.

The steam streams (26, 67) produced by the generators (22, 65) are usedeither in (6) for drying the waste (2) to be treated in treatment unit(78) for cleaning the flue gases and/or for feeding energy to the unitin which this waste is produced.

In this way, the plant discharges to the external environment in (38)only clean flue gases (79) and final waste (77) or ash (68) which can beupgraded, since all the energy produced is converted into steam in orderto be reinjected into the plant or in order to be upgraded upstream.

The gaseous fractions (7) introduced into the first combustion chamber(20) are incinerated at a temperature in the region of 850° C. forapproximately two seconds. As already said, it is important for thegaseous fraction (7) to be conveyed at temperature, in particular byheating the pipeline or injection of a small amount of oxygen in orderto incinerate a portion of the gases. The thermal destruction is thencomplete, which makes it possible to optimize the upgrading of theenergy content of the waste in the form of steam (26, 27).

The plant according to the invention therefore makes it possible totreat with success waste of the most varied types comprising an organicfraction. In addition, and above all, it makes possible an upgradingwith regard to energy of this thermolysis treatment by allowing therecovery in two phases, respectively a gas phase (15) and a solid phase(18), and the combustion of these two phases (20, 60) makes possible theproduction of steam (26, 67) (or hot water) intended to feed the dryer(6) and/or the unit in which the waste (2) is produced. Thus, duringoperation, the plant is virtually autonomous in terms of energy, whichmakes it highly attractive in terms of investment and operation.

FIG. 4 illustrates another simplified embodiment of the invention. Forconvenience, the same references have been used as in FIG. 1. In thisplant, as the waste to be treated exhibits an acceptable level ofmoisture, there is no dryer (6), all the more so since the low capacity(200 kg/h) does not justify heavy investment (specific combustionchamber+dryer).

In this simplified version, in addition to the absence of the dryer (6),there is only one combustion chamber (20). However, it has a twinfurnace, respectively a first furnace for treating the thermolysisvapours introduced via the pipe (17) and a second furnace for treatingthe carbonaceous residues (53) introduced via the conveyor (51). Thissimplified embodiment is advantageous in the treatment of low capacityhospital waste, for example between 100 and 300 kg/h.

FIG. 5 illustrates a second simplified embodiment of the invention. Forconvenience, the same references have been used as in FIG. 1.

In this plant, the waste to be treated is conveyed into a milling unitand is then subsequently dried before being subjected to the thermolysisoperation in the reactor. The gaseous organic fraction obtained isintroduced into a combustion chamber, which chamber feeds a single steamgenerator.

At the same time, the solid carbonaceous products obtained afterthermolysis are screened, making it possible to separate the ferrousmetals by magnetic separation and the non-ferrous metals by magneticinduction, in order to retain only the carbonaceous fraction of thesolid by-product. This carbonaceous fraction is subsequently conveyed tothe combustion chamber, which chamber, on the one hand, produces ashand, on the other hand, feeds the single steam generator.

This simplified embodiment is particularly advantageous in so far as itmakes it possible separately to upgrade the metallic and non-metallicfractions of the solid product obtained after thermolysis.

The plant of the invention, applied to the treatment of meat meal, hasbeen represented in FIG. 6. The same references have been used in thisdiagram as in the other figures.

This plant comprises a unit for the production of meat meal, symbolizedby the reference (1). This unit produces dry meal (2) which is intendedfor estruction as it is unfit for animal consumption. This meal (2) isintroduced into a hopper (4), where it flows under gravity into anisolation means (5), for example a helical compression screw. Thisisolation means (5) is connected to a thermolysis reactor (13) of thetype of that described above.

The reactor (13) is heated at a temperature in the region of 500° C.with a partial vacuum of the order of ten thousand (10,000) pascalsbelow atmospheric pressure and the residence time of the meal in thisreactor (13) is approximately thirty minutes. The thermolysis bringsabout the formation of two products, respectively a gaseous organicfraction recovered upwards via the pipeline (15) and a fraction of solidcarbonaceous residues recovered downwards (18).

The gaseous organic fraction formed during the thermolysis is introducedvia the pipeline (15) into a fan (16) connected in its turn to a firstcombustion chamber (20), for example of the horizontal cylindrical type.This chamber (20) in its turn feeds a first steam generator (22), forexample of the “double circulation boiler”type, connected via a pipe(25) to the unit (1) for the production of meal.

Furthermore, the solid carbonaceous residues (18) formed during thethermolysis are recovered via a pipe (11), such as an endless screwpositioned at the bottom of the reactor (13), in order to introducethese residues into a storage region (50) formed of two tanks, one beingloaded at reduced pressure and the other bringing the residues toatmospheric pressure, these operations being carried out alternately.

The solid carbonaceous residues obtained are rich in carbon but also inpollutants, such as chlorine, sulphur or phosphorus.

These residues exist in the form of a very fine pulverulent powder whichis sieved in (52), for example by passing through screens which make itpossible to reject all the residues having a predetermined size greaterthan a few micrometres, such as, for example, carbonaceous residues ofbones entirely thermolysed during the treatment in the reactor (13). Theaccepted powder is conveyed to the second combustion chamber (60). Onthe other hand, the sieving rejects are reinjected into the hopper (4)and then from there into the reactor (13), for better retention of thepollutants.

The second combustion chamber (60) essentially comprises a specificburner (61) for pulverulent carbon. This chamber (60) in its turn feedsa second steam generator (65) similar to (22). The ash (68) obtained inthe second combustion chamber (60) is disposed of in a landfill site forfinal waste.

The second steam generator (65) is used in combination with a unit forthe treatment of flue gases (78) intended to recover the pollutants (79)in order for them also to be disposed of in a landfill site for finalwaste.

The steam produced by the second generator (65) is introduced via a pipe(62), similar to (25), into the unit (1) for the production of meatmeal, in particular into the unit for drying the meat carcasses or intothe unit intended for drying the meal produced.

In this way, the plant discharges to the external environment only fluegases which are regarded as clean and final waste, since all the energyproduced, converted into steam, is reinjected into the plant and istherefore upgraded.

The gaseous fraction introduced into the first combustion chamber (20)and the solid residues introduced into the second combustion chamber(60) are incinerated at a temperature in the region of 850° C. for atleast two seconds. The thermal destruction is then complete and makes itpossible to optimize the upgrading of the energy content of the meal inthe form of steam used on-site, indeed even partly off-site.

The plant in accordance with the invention exhibits numerous advantageswith respect to those known to date. Mention may be made of:

operational simplicity;

the use of well-proven facilities;

a modular concept allowing easy and fast installation;

the absence of liquid discharges;

excellent safety and good quality of the thermal treatment, since thereis no non-incinerated material;

the fact that, from a waste product, only ash is obtained;

the possibility of carrying out rapid and clean start-ups and shutdowns,with the possibility of placing on standby;

competitive investment costs, low treatment and maintenance costs andthe absence of additional costs related to the treatment intended forwaste water;

a very good upgrading with regard to energy of the waste, since, per 200kilos/hour of hospital waste, it is possible to obtain up to 600kilos/hour of steam at 8 bar or equivalent.

In this way, this plant can be used with success for the treatment ofwaste of any nature, such as domestic, industrial or hospital waste,treatment plant sludges or other wastes, or indeed even at the site onwhich this waste is produced, but without resorting to major plants,which it is known are increasingly expensive and problematic to operateunder conditions under which the environment is respected.

What is claimed is:
 1. Plant for the destruction by thermolysis of meatmeal (2) and the combustion of the meal to produce steam that includes:a unit for the production (1) of meat meal from animal carcasses; acontinuous feed isolation means (5) and a gravity hopper (4) for feedingthe meal produced to a reactor; said reactor for the thermolysis (13) ofthe meal thus produced; means (15,16) for recovering, at the top of thereactor (13), the gaseous organic fraction formed during the thermolysisand for introducing this gaseous fraction into a first combustionchamber (20) feeding a first steam generator (22); means (11) forrecovering, at the bottom of the reactor (13), the solid carbonaceousresidues formed during the thermolysis and for introducing these solidresidues into a second combustion chamber (60) in its turn feeding asecond steam generator (65); said two steam generators (22, 65) in turnfeeding energy to the unit for the production (1) of meat meal.
 2. Aplant for processing waste having an organic fraction and for reusingwaste energy in the process, said plant including loading means forintroducing waste into a waste treatment system containing a stationary,non-rotatable reactor for thermal dissociation of said waste bythermolysis under a reduced pressure and at a elevated temperature, saidsystem further includes: means for isolating the waste input and outputto the reactor to maintain said reduced pressure in said reactor and toinsure said thermolysis reaction is carried out in an atmosphere havinga low oxygen content, a gas recovery means in the upper section of saidreactor for recovering a gaseous organic fraction from the reactor andintroducing the gaseous faction into a first combustion chamber of afirst steam generator, a solid recovery means in the lower part of saidreactor for recovering solid carbonaceous materials from said reactorand introducing said solid materials into a second combustion chamber ofa second steam generator, preheating means for placing exhaust gasesform said first and second combustion chambers and steam from said firstand second steam generators in heat transfer relation with said wasteprior to introducing said waste into said reactor to preheat said waste,and means located between the preheating means and the reactor foradding an agent to said waste for neutralizing of components containedin the waste.
 3. The plant of claim 2 that further includes means tomill said waste to bring the waste to a homogenous particle size priorto introducing said waste into said reactor.
 4. The plant of claim 2wherein said reactor operates at a temperature of between 400 g and1000° C. and a pressure of 5000 and 40,000 pascals in the absence ofoxygen.
 5. The plant of claim 2 having further means for separating thesolid carbonaceous materials recovered from said reactor into acombustible product and a non-combustible product and delivering thecombustible product to said second combustion chamber.
 6. The plantaccording to claim 5 that further includes a treatment unit for gasesexhausted from said second steam generator for recovering pollutants insaid exhaust gases to prevent said pollutants from being discharged intothe atmosphere.